Apparatus for supplying air into combustion chamber of rotary kiln incinerator

ABSTRACT

An inner drum extending axially through a cylindrical kiln is comprised of a hollow cylinder, and a hollow reinforcement structure closely fitted in the cylinder to prevent same from sagging at elevated temperatures. The reinforcement structure is cooled by the water flowing therethrough and may be substantially cruciform in cross section, dividing the interior of the cylinder into a plurality of air channels adapted to supply air into the kiln through a number of bores formed in the cylinder. The air channels are intercommunicated by a plurality of passageways extending through the reinforcement structure and/or by a hollow space formed at one or both ends of the cylinder in order to reduce fluctuations in the pressure or volume of air supplied thereto.

United States Patent, 11 1 Sugano et al.

APPARATUS FOR SUPPLYING AIR INTO COMBUSTION CHAMBER OF ROTARY KILN INCINERATOR Inventors: Kumakichi Sugano, 34-6, 3-chome,

Asakusabashi, Daito-ku; Masanao Sugano, 22-5, l-chome, Ojima Koto-ku, both of Tokyo, Japan Filed: Oct. 20, 1972 Appl. No.: 299,331

us. or 110/10, 110/14, 432/116 Int. Cl. F23g 5/06 Field of Search 110/14, s, 10, 18;

References Cited UNITED STATES PATENTS 5/1890 Clark 110/14 12/1933 Hougen et al. 432/114 Windecker l lO/l4 11 1 3,808,988 1451 May 7,1914

Primary Examinerl(enneth W. Sprague Assistant Examiner-Henry C. Yuen Attorney, Agent, or Firm-Eric H. Waters [5 7] ABSTRACT An inner drum extending axially through a cylindrical kiln is comprised of a hollow cylinder, and a hollow reinforcement structure closely fitted in the cylinder to prevent same from sagging at elevated temperatures. The reinforcement structure is cooled by the water flowing therethrough and may be substantially cruciform in cross section, dividing the interior Of the cylinder into a plurality of air channels adapted to supply air into the kiln through a number of bores formed in the cylinder. The air channels are intercommunicated by a plurality of passageways extending through the reinforcement structure and/or by a hollow space formed at one-or both ends of the cylinder in order to reduce fluctuations in the pressure or vol ume of air supplied thereto.

6 Claims, 4 Drawing Figures PATENTEUMAY 7 m4 sum 2 or 3 APPARATUS FOR SUPPLYING AIR INTO COMBUSTION CHAMBER OF ROTARY KILN INCINERATOR This invention relates generally to incinerators, and in particular to improvements in an inner drum extending axially through a cylindrical kiln to supply air into the interior thereof in a rotary kiln incinerator of the hype disclosed in our copending US. patent application Ser. No. 214,063, filed Dec. 30, 1971, US. Pat. No. 3,749,033.

In the rotary kiln incinerator disclosed in our copending patent application, the kiln is automatically rotated at controlled speed to cause agitation and intimate mixing of the refuse with combustion air. Further, as the kiln rotates, a number of fins secured in substantially helical arrangement on its inner surface function to feed a charge of refuse from one end of the kiln to the other end where a discharge opening is formed, so that no hardened residue remains adhered to theinner surface of the kiln. With a view to complete combustion of rubber, leather, plastics and like substances which would produce a great deal of smoke and/or poisonous gases if burnt incompletely, a sufficient amount of combustion air is supplied to all parts of the combustion chamber within the kiln from the inner drum extending axially therethrough.

Although the proper functioning of this inner drum is thus essential for the successful operation of the rotary kiln incinerator as a whole, the inner drum has still some problems that remain unsolved. One of the problems concerns its resistivity to heat and another concerns its manufacture;

Regarding first the heat resistivity of the inner drum, it must be taken into account that synthetic resins and some other substances produce as high a temperature as about 2,000 C when combusted completely, as compared with the melting point of steel employable for the manufacture of the inner drum which is at about 1,530? C. This problem is overcome, in part, in the inner drum of the rotary kiln incinerator disclosed in the aforementioned U. S. patent application Ser. No. 214,063, in which there is provided a water conduit having a plurality of circumferentially spaced-apart projections extending in parallel relationship throughout the length thereof to define air channels therebetween from which air is supplied into the combustion chamber. However, due to the weight of the cooling water within this conduit, plus the decrease in the strength or rigidity of the inner drum itself at elevated temperatures during operation of the incinerator, the inner drum inevitably tends to sag in the middle, thereby giving rise to the possibility of plastic deformation or, at the worst, burning down altogether.

As regards manufacture, it will be apparent that the inner drum of prior design must be formed by intricate welding operations which require a prohibitive expenditure of time and labor. Moreover, if the above noted trouble happens to the inner drum thus manufactured at great cost, it usually requires complete replacement, there being no way of repair or at least partial replacement.

With these and other difficulties and inefficiencies of the prior art in mind, it is an object of thepresent invention to provide a novel and improved inner drum adaptable for supplying a sufficient amount of air into the combustion chamber of an incinerator by being positioned within the combustion chamber itself.

Another object of the invention is to provide an inner drum of the character referred to, in which a reinforcement structure defining a cooling water chamber therein is closely fitted in a hollow cylinder so as to divide the interior of the cylinder into a plurality of air channels from which air is supplied directly into a combustion chamber of an incinerator, so that the strength or rigidity of the inner drum at elevated temperatures is highly increased without hampering its performance.

A further object of the invention is to provide an inner drum of the character referred to,'in which the hollow cylinder and the reinforcement structure therein are cooled separately by different cooling media to prevent them from deforming or fracturing at elevated temperatures.

A further object of the invention is to provide an inner drum of the character referred to, in which the hollow cylinder and the reinforcement structure are united together in a readily separable manner to permit easy repair and partial replacement of either the cylinder or the reinforcement structure as required.

A further object of the invention is to provide an inner drum of the character referred to, which can be mass-produced at greatly reduced costs.

With these objects in view and the other objects, features and advantages of the present invention hereinafter made apparent, the invention will now be described more specifically in conjunction with the accompanying drawings which illustrate, by way of example only, a preferredembodiment thereof, and in which:

FIG. 1 is a side elevational view of a rotary kiln incinerator incorporating an inner drum according to the novel concepts of the present invention, with parts thereof being shown broken away to show other parts in detail;

FIG. 2 is an enlarged cross-sectional view of the inner drum of FIG. 1;

FIG. 3 is a longitudinal sectional view of the inner drum taken along the planes of line Ill III in FIG. 2; and

FIG. 4 is a'partial perspective view of an explanatory nature showing the inner drum and a kiln in the rotary kiln incinerator of FIG. 1.

An example of a rotary kiln incinerator to which are applicable the novel concepts of this invention will now be briefly described with reference to FIG. 1 in order to make clear the functions of the inner drum which is the subject of this invention. A kiln l0 -of generally hollow cylindrical form is conventionally made of steel plate having a thickness of, say, about 12 millimeters.

The kiln 10 may have an internal diameter of about 800 This circular opening 14 is closed by a separately formed faceplate l6 kept stationary by suitable means regardless of the rotation of the kiln 10. The faceplate 16 is formed'with an exhaust opening 17 therethrough to communicate the interior of the kiln 10 with a chimney 18 supported by frame means 19. A charging opening 20 having a hinged door 21 is also formed through the'faceplate 16.

A hollow cylindrical member 22 having an internal diameter of about 400 millimeters and an axial length of about 300 millimeters is affixed, as by welding, to the closed left hand end of the kiln coaxially therewith. Mounted circumferentially on the left hand end of the member 21 is a sprocket 23 linked by a chain 24 to another sprocket 25 on the output shaft of a speed reducer unit 26 adapted for sufficiently reducing the revolving speed of a motor 27. Hence the kiln 10 may be revolved at a rate of from about 1 to 1.5 revolutions per minute.

A number of fins 28 are fixed in substantially helical arrangement on the inside surface of the kiln 10. As the kiln rotates, therefore, the refuse introduced through the opening 20 at one end thereof will be fed. by these fins 28 toward the other end of the kiln while being properly agitated. For the discharge of the burnt ashes of the refuse thus fed by the fins 28, a discharge opening 29 is formed adjacent the said other end of the kiln 10. Since it is desirable to keep this discharge opening closed as long as possible in order to maintain an appropriate volume of air within the'kiln 10, an annular member 30 is fixedly supported along the path traced by the discharge opening as the kiln rotates, and an openable door having a roller (both not shown) in internal slidable contact with the annular member is provided to the discharge opening. The annular member has its lowermost position suitably recessed or broken away, in such a manner that the door will be opened only when its roller is received in this recessed or broken away portion of the annular member during rotation of the kiln 10.

Extending axially of the kiln 10, an inner drum generally indicated by the numeral 31' is illustrated here by way of a preferred embodiment of the invention hereinafter described in more detail. Typically, the inner drum 31 may have an external diameter of about 350 millimeters and an axial length of from about 3,000 to 3,500 millimeters, and may be fixedly supported at its right hand end by the stationary faceplate 16 and at its left hand end by support means 32 on a floor or base 33, the kiln l0 beingrotated relative to this inner drum.

1 of bores (not shown in FIG. 1) formed in the inner drum 31 and while being both agitated and fed toward the-discharge opening 29 by the fins 28 as the kiln 10 rotates.

As illustrated in greater detail in FIGS. 2 to 4, the improved inner drum 31 according to this inventionincludes a hollow cylinder 34 anda hollow structure 35 of substantially cruciate across section snugly fitted therein for reinforcement purposes. As best shown in FIG. 2, the structure 35 defines a cooling water chamber 36 therein and further devides the interior of the cylinder. 34 into a plurality of air channels 37 which are intercommunicated in amanner hereinafter described. It must be noted that the cross-sectional shape of the structure 35 is not limited to the example disclosed herein; indeed, it may have any suitable number of annularly spaced radial extensions 35a on its core portion 35b for making close internal contact with the cylinder 34.

With particular reference to FIG. 3, the length of the structure 35 may be made smallerthan that of the cylinder 34, in order to leave a space 38 at least at one end thereof intercommunicating the air channels 37. However, it is important that the length of this structure 35 be appropriately longer than the spacing between the faceplates 13 and 16 of the kiln 10, FIG. 1, supporting the inner drum 31 so that the structure 35 itself can be securely supported by these faceplates 13 and 16. Both ends of the structure 35 are closed and have a water inlet 39 and a water outlet 40, respectively, extending through faceplates 41 which are secured, as by bolting, to both ends of the cylinder 34 upon insertion of the structure 35 therein.

An air inlet 42 formed through one of the faceplates 41 of the cylinder 34 communicates with-a blower, not shown or the like, via suitable means for regulating the pressure and the volume of air supplied therefrom. The combustion air thus delivered into the space 38 at one end of the cylinder 34 flows into the air channels 37 and thence into the combusion chamber within the kiln 10 through a number of bores 43 formed at suitable spacings through the cylinder 34. Each of the bores 43 in this particular embodiment of the invention may have a diameter of about 26 millimeters for the best results. In order to reduce the fluctuations in the pressure .and the volume of combustion air thus supplied into the air channels 37, a plurality of spaced-apart passageways 44 may be formed through each of the radial extensions 35a of the structure 35 for intercommunicating these air channels, although the provision of the space 38 at one or both ends of the cylinder 34 is also conductive to this end.

In order to supply cooling water into the chamber 36, the aforesaid water inlet 39 may be communicated with a pump, not shown, or the like via suitable means for regulating the pressure and the volume of water supplied therefrom. The cooling water thus introduced into the structure 35 will flow through the chamber 36 and will exit through the water outlet 40.

For the assemblage of the inner drum 31 constructed as above described,-the hollow cylinder 34 and the structure 35 are first prepared separately. While the hollow cylinder 34 may be readily available as such, the structure 35 must be formed by welding operation which may be performed at W as indicated in FIG. 2. As may be seen from this drawing, all the constituent members of the structure 35 are of the same size and shape, so that they can be roll-formed to the same dimensional specifications. Moreover, the thus-formed constituent members of the structure 35 can be easily welded together, as by means of a fully automatic welding machine. Upon insertion of this structure 35 into the hollow cylinder 34 there is completed the inner drum 31.

As may now be apparent, the hollow cylinder 34 in the improved inner drum 31 of this invention is to be cooled not so much by the cooling water within thethe rigidity or strength of the entire inner drum 31. It is therefore unnecessary to make the capacity of the water chamber 36 inordinately large, because too much weight of the water contained therein may tend to cause sagging of the structure 35 and hence of the hollow cylinder 34. The capacity of the water chamber 36 should be reduced only insofar as the volume of water held therein is sufficient for duly cooling the structure 35.

While it will be apparent that the various explicitly stated and implicitly suggested objects of the present invention are fully accomplished by the improved inner drum herein disclosed, it must also be understood that a latitude of modification, substitution and change is intended in the foregoing disclosure. Moreover, in some instances, some features of the invention will be employed without a corresponding use of other features, while still remaining in the proper scope or fair meaning of the appended claims.

We claim:

1. An arrangement in an incinerator comprising a kiln; plate means for closing opposite ends of said kiln to form a combustion chamber therein; and an inner drum extending through said kiln to supply air into 'said combustion chamber, said inner drum comprising: a hollow cylinder having a number of bores, and a reinforcement structure closely fitted in said cylinder for preventing said cylinder from sagging at elevated temperatures, said reinforcement structure being hollowed for forming a cooling water chamber and dividing the interior of said cylinder into a plurality of air channels to supply air into said combustion chamber through said bores in said cylinder.

2. The arrangement according to claim 1, wherein said reinforcement structure includes a core portion extending substantially axially of said cylinder, and a plurality of radial extentions formed lengthwise on said core portion for making close internal contact with said cylinder.

3. The arrangement according to claim 2, including a plurality of passageways formed through each of said radial extentions to intercommunicate said air channels.

4. The arrangement according to claim 2, wherein the length of said reinforcement structure is smaller than that of said cylinder for leaving a hollow space at least at one end of said cylinder, said hollow space communicating with said air channels.

5. The arrangement according to claim 4, wherein the length of said reinforcement structure is greater than the spacing between said plate means closing opposite ends of said kiln; said plate means supporting said reinforcement structure.

6. The arrangement according to claim 1, wherein said reinforcement structure is of substantially cruciate cross section. 

1. An arrangement in an incinerator comprising a kiln; plate meaNs for closing opposite ends of said kiln to form a combustion chamber therein; and an inner drum extending through said kiln to supply air into said combustion chamber, said inner drum comprising: a hollow cylinder having a number of bores, and a reinforcement structure closely fitted in said cylinder for preventing said cylinder from sagging at elevated temperatures, said reinforcement structure being hollowed for forming a cooling water chamber and dividing the interior of said cylinder into a plurality of air channels to supply air into said combustion chamber through said bores in said cylinder.
 2. The arrangement according to claim 1, wherein said reinforcement structure includes a core portion extending substantially axially of said cylinder, and a plurality of radial extentions formed lengthwise on said core portion for making close internal contact with said cylinder.
 3. The arrangement according to claim 2, including a plurality of passageways formed through each of said radial extentions to intercommunicate said air channels.
 4. The arrangement according to claim 2, wherein the length of said reinforcement structure is smaller than that of said cylinder for leaving a hollow space at least at one end of said cylinder, said hollow space communicating with said air channels.
 5. The arrangement according to claim 4, wherein the length of said reinforcement structure is greater than the spacing between said plate means closing opposite ends of said kiln; said plate means supporting said reinforcement structure.
 6. The arrangement according to claim 1, wherein said reinforcement structure is of substantially cruciate cross section. 